FOLDING DOOR

PROBLEM TO BE SOLVED: To provide a folding door, in detail, a folding door automatically closed after it is opened having a simple structure, reducing the size of elongation of a tension spring, facilitating the open operation of a door exerting automatically closed movement without rapidly closing the door and maintaining a complete closed posture. SOLUTION: In a folding door 100 constituted of a first door 2 bearing an open side end in a rotatable manner and a second door 3 connecting the open side end to the first door 2 in a foldable manner and having the upper part thereof borne on a fixed member in a slidable manner in an openable direction, while a second pivot rotating together with the second door 3 and slidable in the openable direction is provided to the upper part of the second door 3, and an energizing device 9 rotating the second pivot in the direction closing the second door 3 is always provided in a position where it moves together with the second door 3.